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(No Model.) 3 Sheets-Sheet 1. D. E. SWEET.

ELECTRIC MOTOR.

Patented Deo. 25, 1888.

NN A il ttorney (No Model.) 3 Sheets-Sheet 2.

' D. E. SWEET. Y

ELECTRIC MOTOR. No. 395,299. Patented Deo. 25, 1888.

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WITNESSES IN VENTOR @af/792.9550825 /ffi/ ai ttorrzey (No Model.) 3Sheets-Sheet 3.

D. I'. SWEET.

ELECTRIC MOTOR.

190.395.299. Patented Deo. 25, 1888.

zifyza @www TNESSES I MENTOR I y' J4" La A Y M ./ttorney UNITED STATESPATENT EEICE,

DANIEL FREDRICK SIYEET, OF GRAND RAPIDS, MICHIGAN, ASSIGNOR TO MARCUSIY. BATES, OF SAME PLACE.

ELECTRIC MOTOR.

SPECIFICATION forming part of Letters Patent No. 395,299, dated December25, 1888. Application filed December 15, 1387. Serial No. 253,006. (Nomodel.)

To a/ZZ 207mm it' may con/certa Be it known that I, DANIEL FEEDR'IOKSWEET, a citizen of the'United States, residing at Grand Rapids, in thecounty of Kent and State of Michigan, have invented certain new anduseful Improvements in Electric Motors, of which the following is aspeciiication, reterence being had therein to the accompanying drawings.

` Thisl invention relates to certain improvements in electric motors, orgenerators and motors; and it has for its objects to so arrange therotating' armatures in conjunction with the iield magnet or magnets asto concentrate the magnetic forces in the field, as more vfullyhereinafter speciiied.

It is a well-known fact that the attractive force of a magnet is mainlyat its polar eX- tremities, and especially at the corner or salientpoints ot' the saine, and it is also known that the attractive points inthe armature also are at the polar extremities ot the same and theirsalient points or angles. My invention is designed to render ettectivethese wellknown laws ot magnetism in the construction of an electricgenerator or motor by so arranging the rotating armature andfield-magnets, respectively, as to concentrate the lines of magneticforce between the polar extremities of the Held magnet or magnets andthe rotating armatures of the machine, whereby the greatest possibleamount of electro-motive force is utilized and a compact and powerfulmachine is produced.

The invention further has t'or its objects to so construct thecommutators as to prevent r the usual spark and the consequent corrosionor burning ot' the surfaces ot the commutatorbrnshes andcommntator-disks, as will lbe more t'ully hereinafter explained.

The invention further has t'or its objects to l prevent thcburning ontot' thc wires on the armatures, so that, in case olf too great acurrent, thc said wire will be burned outside oi the coil, where it canbe easily connected with the commutators, and obviate the rewinding ofthe armatures in case ot' injury, and the consequent taking apart andrebuihling of the machine.

The invention further relates to certain im- 1 magnets. 4 section ot'one ot the commutator-dislts; Fig.

provements in the construction of the fieldmagnets, whereby provisionmade for more conveniently applying the coils to such mag'- nets, themagnets are rendered more effective, and the full magnetic force of themagnet between its poles and those ot' the armature is utilized ininducing' the currents in the coils of the armatures, and, further, toprevent counter-currents in the coils ot' the field-magnets bypreventing the vibration of the same, due to the mutual attraction andrepulsion ot' the said magnets and armatures; and to an improved methodof mounting the magnets so that they will be magnetically insulated, andwill consequently have no direct influence upon each other; and theinvention still further relates to certain improvements in theconstruction ot' the ar1na tures, by which an enlarged area of polarsurface is secured, and more forcible currents induced in the coils, aswill be more fully hereinafter specified.

The above-mentioned objects I attain by the means illustrated in theaccompanying drawings, in which- Figure l represents a view which ispartly a section and partly a side elevation ol a motor constructedaccording to my invention. Fig. 2 represents a top view ot the same.Fig. 3 represents a sectional view of the armature and one of thesupportingheads in elevation. Fig. I represents a perspective view ot'one ot` the field-magnets with the coils removed, showing one ot" thesleeves upon which the coils are wrapped. Fig. 5 represents a transversesectional view ot' one ot the iield- Fig. 6 is a perspective view of a7, a detached perspective view ot one ot' the armature-bars; Fig. S, aperspective view ot' a l'rame or yoke which elnbratl-cs the poles of thetiehl-magnet. Fig. t represents a vertical sectional view ot' a pm'tionot" one of the held-magnets; and Fig. lo, a bottom view ot the motor,showing the circnit-connections.

The letter A indicates the base ot' the machine, which is constructed ofwood or other non-magnetic material, and lii the field-magnets, whichare constructed ot' rectangular bars b, of sot't iron, bent, as plainlyshown in IOO Fig. 4 of the drawings, the vertical arms being surroundedwith sleeves C, constructed of sheets or strips of iron coated withnonmagnetic material. The said strips are wrapped around the arms of themagnets in such a manner as to expose their upper edges, a, insuccessive layers, one slightly above the other, for the purpose offorming a series of polar extremities. E indicates a yoke or frame, ofnon-magnetic material, which extends around and embraces the polarextremities of the field-magnets, and which is rigidly fastened to saidmagnets by. means ot screws or otherwise, so as to prevent the vibrationof the arms of the magnets and the production of inducedcounter-currents in the coils ot said mag'nets, which would interferewith the main current from the generator. The yoke or frame is providedwith extensions F, having bearings at their extremities for the shaft Gof the rotating armatures. The said shaft has mounted on it the disks orheads H, of non-magnetic material, the said heads being provided withrectangular seats 7i, as shown in Fig. 3 ot the drawings, at suitableintervals on their peripheries for the polar extremities ot' thearmature I, which are iirmly secured to the heads or disks by means ofscrews or otherwise. The said armatures are rectangular incross-section, except at their extremities, which on their outersurfaces are turned oft, as shown at d, to a curve corresponding' withthat of the peripheries of the disk, the metal being' grooved at theshoulders, as indicated by the letter K, so as to form magnet-poles backof the polar extremities ot' the armatures, the object of which is toconcentrate the lines of magnetic force in the magnetic field, as willbe more vfully hereinafter explained, thc groove d in the armaturesbeing located just at the point where such armatures begin to projectIfrom their coils, as plainly shown in Fig. l ol" the drawings. Therectangular portions ot' the armatures are wrapped with insulated wires,the mass in each being narrowed toward the shoulders of the armatures,forming' al1 oval bodyin longitudinal section, as shown in Fig. l ot'the drawings, and the armatures, with their surrounding coils, areinelosed in a eontinuous wrapping of suitable material to give the wholea smooth external surface to permit the armatures to rotate with aslittle atmospheric resista-nce as possible. The wires of thearnmture-eoils are carried out through suitable openings in the headadjoining the commutators, the openings being lined with a suitableinsulatin g-bushing, M, the wi res being coiled within the bushing, andconnected at their outer ends with the wire N, leading to thecommutator-disks, the said wires N being of less diameter than those ofthe armature-coils, so as to otter a resistance to this current at theoutside of the head, by means of which the armature-wires under theinlinence of any excessive current will burn out at the outside of thecoils instead of within the same, where the damage .may be rapidlyrepaired by drawing out the armature-wires and reconnecting them withthe commutatorwires, thus avoiding the necessityv of taking apart themachine and rewinding the armatures, as would be the case it' the wiresshould be burned or damaged within the coils.

The eomn'iutator-disks are made in sections P, as shown in Fig. 6 of thedrawings. The said sections are grooved at their peripheries and securedaround the armature-shaft by a wrapping of cord, thread, or othernon-conducting material. The said cord does not come flush with theperiphery of the disk, leaving air-spaces around the disks, whichprevent the spark which usually takes place between the brushes anddisks as ordinarily constructed. The connnutator-brushes R are confinedto the cross-heads S ot' the metallic posts T, which extend through thebase of the machine.

The circuits, as shown in outline in Fig. l0, are as follows: Thecurrent from the battery enters the binding-post- V, thence by wire lVto one ot' the pairs of field-magnets, through the same, alongI wire Ato a switch, X, to wire B', to one of the posts T, to commutatorbrushesand armature, to the other post T, to wire C', to post U, to battery.\Yhen the switch is moved, the current enters the post V, then passes towire XV, to one pair of fieldmagnets, as before, to wire D', to theother pair of field-magnets, to wire F', to switch, to wire B', to postT, to eommutator-brushes and armatures, to other post- T, to wire C', topost U, to battery. Thus the switch may be operated to bring' one orboth pairs oi lield` magnets into the circuit.

It will be seen that the grooves and shoulders on the polar extremitiesso direct the lines ot' :force in the field that the entireelectromotive force is concentrated between the poles ot' the armatureand field magnets, and is thereby entirely utilized.

Having thus l'ully described my invention, what I claim as new, anddesire to secure by Letters Patent, is-

l. Afield-magnet for an eleetricmotor, consisting of a rectangular barof iron bent as described, wound with coils of sheetiron, as described,and having its polar extremities extended beyond the surrounding' coils,so that they may extend at each side of the polar extremities ot' thearmatures,substantially as specified'.

2. An armature for an electric motor, consisting' of a rectangular barof sott iron having' its ends turned oft', as described, and groovedtransversely at the shoulder formed by the turned portion, substantiallyas set forth.

3. The combination, with the armature= shaft, of the commutatorsectionsgrooved on their peripheries and suitably insulated, the non conducting'wrappings wound in said IOO IIO

`grooves, whereby the sections are held together so as to leaveperipheral air-Spaces, substantially as Specified.

4. The Combination, with bars of the eldmagnets7 of the sleevesconsisting' of strips of Sheet-iron coated with nen-magnetic materialand Wrapped around the magnet-hars, Substantially as speeied.

5. The Combination, with the field-magnets,

.Io 0f the sleeves consisting' of Strips ol' heetz- A iron coated with anon-magnetic Covering and having` a series ot' successively-exposedpolar edges extending` above the coils ot' the mag'- nets,substantiall)v as set forth.

In testimony whereof l affix my Signature in I5 presence ot' twowitnesses.

DANTEL 'FREDRICK SXVEET. lYitneSSeS:

FRED XV. STEVENS, BLOSSIE SMITH.

